Fan for an apparatus for the regulated delivery of a gas, in particular oxygen

ABSTRACT

This fan ( 1 ) includes a volute ( 2 ) whose inlet opening ( 3 ) is in communication with the oxygen feed line, an impeller ( 4 ) situated immediately downstream of the inlet opening of the volute and including an inlet opening connected to this inlet opening ( 3 ) of the volute and outlet orifices ( 4   a ) emerging into the volute ( 2 ), and an electric motor ( 5 ) for rotating the impeller ( 4 ). The fan ( 1 ) includes: —a compartment ( 6 ) in which the motor ( 5 ) and, where appropriate, other electric elements or components belonging to the fan ( 1 ) are placed, this compartment ( 6 ) including an end wall ( 13 ) traversed by the shaft of the motor ( 5 ) and being supplied with pressurized air, and—a leak collection chamber ( 7 ) situated intermediately between the volute ( 2 ) and the compartment ( 6 ), this chamber likewise being traversed by the shaft of the motor ( 5 ) and including a discharge orifice ( 20 ).

The present invention relates to a fan used in an apparatus for theregulated delivery of a gas, in particular oxygen. This apparatus mayespecially be a respiratory assistance apparatus.

A fan delivering gases other than air, especially oxygen, conventionallycomprises a volute whose inlet opening is in communication with theoxygen feed line, an impeller situated immediately downstream of thisinlet opening and comprising an inlet opening connected to this inletopening of the volute and outlet orifices emerging into the volute, andan electric motor for rotating the impeller.

The rotation of the impeller generates a centrifugal oxygen flow whichis converted into increased gas pressure in the volute.

There is a major problem in this type of fan of oxygen leaking in thedirection of the electric motor through the gap which necessarily existsbetween the shaft of the motor and the wall of the volute that istraversed by this shaft. Oxygen penetration in the direction of themotor or other electric elements or components of the apparatusresulting from such a leak is not acceptable on account of the risk ofignition which could result therefrom; moreover, the standards of acertain number of countries prohibit the presence of oxygen in aproportion of more than 26% in those regions of a medical apparatus thatinclude electric circuits.

The main objective of the invention is to solve this problem under thebest conditions.

There is also a problem of cooling the electric motor in the existingfans, this motor being subject to significant heating on account of itshigh speed of rotation.

Another objective of the invention is to overcome this problem under thebest conditions, in combination with tackling the aforementioned leakageproblem.

The fan in question comprises, in a manner known per se, a volute whoseinlet opening is in communication with the oxygen feed line, an impellersituated immediately downstream of the inlet opening of the volute andcomprising an inlet opening connected to this inlet opening of thevolute and outlet orifices emerging into the volute, and an electricmotor for rotating the impeller.

According to the invention, the fan comprises:

-   -   a compartment in which the motor and, where appropriate, other        electric elements or components belonging to the fan are placed,        this compartment comprising an end wall traversed by the shaft        of the motor and being supplied with pressurized air, and    -   a leak collection chamber situated intermediately between the        volute and the said compartment, this chamber likewise being        traversed by the shaft of the motor and including a discharge        orifice.

Thus, the motor and any other electric elements or components of the fanare placed in a compartment containing pressurized air, this air flowingout of this compartment through the gap which necessarily exists betweenthe shaft of the motor and the said end wall. This flow of pressurizedair makes it possible to oppose the ingress into the compartment ofpressurized oxygen flowing through the gap which necessarily existsbetween the shaft of the motor and the wall of the volute that istraversed by this shaft.

These respective air and oxygen leaks are collected in the collectionchamber and can be discharged by simply flowing through a dischargeorifice belonging to this collection chamber.

Preferably, the shaft of the motor comprises at least one deflectormember for separating the respective air and oxygen flows and fororienting these flows, on leaving the said gaps, in directions which aresubstantially perpendicular to the shaft of the motor.

Disturbances between these flows are thus eliminated, and the risk ofoxygen penetrating into the compartment is also reduced, notwithstandingthe pressure of the oxygen flow, which is substantially higher than thatof the air flow.

The air flowing into the compartment can be advantageously pressurizedby an impeller arranged opposite the air inlet opening belonging to thiscompartment. Advantageously, in this case, this impeller is arranged onthe drive shaft for the impeller situated in the volute. It is thereforedriven by the same motor.

The walls defining the compartment can comprise one or more openingsemerging directly into the said collection chamber.

This opening or these openings allow a flow of pressurized air aroundthe motor and then into the collection chamber, thereby making itpossible to cool the motor. The flow of this air into the collectionchamber additionally allows a rapid discharge of the mixture of air andoxygen present in this chamber.

Preferably, the compartment comprises an internal transverse wall whichis distinct from the aforementioned end wall and which is perforated byat least one hole for the flow of air across this wall.

This internal transverse wall and this end wall thus define between thema secondary air flow chamber, and the hole or holes belonging to thesaid internal transverse wall optimize the pressurization of thissecondary chamber so as to allow the leak at the said gap to occur underthe best conditions. This leakage rate thus remains effective, using therelatively high air pressure created in the secondary chamber.

The said internal transverse wall can in particular be formed integrallywith other walls defining the compartment and serve to centre the motorin this compartment.

The said end wall can be composed of a thin plate.

With the same aim, the wall of the volute that is traversed by the shaftof the motor can also be composed of a thin plate adapted to theprecision required for obtaining a small clearance at the level of thesaid gap situated where the shaft passes into the volute wall.

The leaks collected by the collection chamber can be purely and simplydischarged, or can be recycled, in which case the discharge orifice ofthe collection chamber can be connected directly to the oxygen feedline.

In this same case of recycling the collected leaks, the collectionchamber is advantageously divided into two adjoining subchambers, one ofwhich, situated adjacent to the volute, is mainly intended to collectthe flow of oxygen coming from this volute and the other of which,situated adjacent to the said compartment, is mainly intended to collectthe flow of air coming from this compartment, each subchamber comprisinga discharge orifice which is specific to it.

Thus, the subchamber situated adjacent to the volute mainly collects theoxygen flow, which can be recycled by placing the discharge orificebelonging to this subchamber in communication with the oxygen feed line.

The invention will be properly understood and other features andadvantages thereof will become apparent with reference to the appendedschematic drawing which represents, by way of non-limiting examples, anumber of possible embodiments of the apparatus to which it relates.

FIG. 1 is a view in axial section thereof, according to a firstembodiment;

FIG. 2 is a detail view thereof, on an enlarged scale;

FIG. 3 is a view in axial section thereof, similar to FIG. 1, accordingto a second embodiment;

FIG. 4 is a detail view thereof, on an enlarged scale, according to thissecond embodiment;

FIG. 5 is a view in axial section thereof, similar to FIG. 1, accordingto a third embodiment; and

FIG. 6 is a detail view thereof, on an enlarged scale, according to thisthird embodiment.

For reasons of simplification, those parts or elements of one embodimentwhich reappear in an identical or similar manner in another embodimentare designated by the same reference numbers and are not describedagain.

FIGS. 1 and 2 represent a fan 1 used in an apparatus for the regulateddelivery of a gas, in particular oxygen, it being possible especiallyfor this apparatus to be a respiratory assistance apparatus.

The fan 1 conventionally comprises a volute 2 whose inlet opening 3 isin communication with an oxygen feed line (not shown in this figure), animpeller 4 situated immediately downstream of this inlet opening 3 andcomprising an inlet opening connected to this opening 3 and outletorifices 4 a emerging into the volute 2, and an electric motor 5 forrotating the impeller 4.

The bottom of the volute 2 is defined by a wall composed of a thin plate2 a traversed by the shaft of the motor 5. There is a gap between thisshaft and this plate 2 a, through which pressurized oxygen contained inthe volute 2 inevitably flows.

As is represented, the fan 1 also comprises a compartment 6 and a leakcollection chamber 7.

The compartment 6 contains the motor 5 and also, where appropriate,other electric elements or components belonging to the fan 1. Itcomprises an air inlet 10, a number of openings 11 emerging directlyinto the collection chamber 7, a transverse wall 12 and an end wall 13.

The air inlet 10 is situated on that end of the compartment 6 which isopposed to the volute 2, and is coaxial with the shaft of the motor 5including the impeller 4. Immediately downstream of this inlet 10, thefan 1 comprises an impeller 15, smaller than the impeller 4, arranged onan extension of the shaft of the motor 5 which includes the impeller 4.

As will be understood, the rotation of this impeller 15 by the motor 5makes it possible to create a pressurized air circulation in thecompartment 6; this air passes into the collection chamber 7, for themost part through openings 11, and for the minor part through holes 16belonging to the wall 12 and through the gap which exists between thehub of a deflector member 17 belonging to the shaft of the motor 5 andthe end wall 13.

In this illustrated example, the openings 11 are formed in theperipheral wall defining the compartment 6, perpendicularly to the shaftof the motor 5.

The transverse wall 12 is formed integrally with this peripheral walland serves to centre the motor 5 in the compartment 6.

The end wall 13 for its part is composed of a thin plate. This wall 13is fastened to a rim belonging to the fan 1 in the continuation of theperipheral wall defining the compartment 6, such that it is located at adistance from the wall 12 and such that it defines a secondary air flowchamber therewith. The holes 16 belonging to the transverse wall 12optimize the pressurization of this secondary chamber so as to allow anair leak at the aforementioned gap.

The collection chamber 7 is situated between the volute 2 and thecompartment 6, encompassing the upper part thereof. It is traversed bythe shaft of the motor 5 and includes a discharge orifice 20.

The deflector member 17 comprises, in addition to the aforementioned hubwhich serves to mount it on the shaft of the motor 5, a part in the formof a flange formed integrally with this hub. As is shown moreparticularly in FIG. 2, this deflector member 17 makes it possible toseparate the respective air and oxygen flows coming from theaforementioned respective gaps and to orient these flows, on leaving thesaid gaps, in directions which are substantially perpendicular to theshaft of the motor 5.

As is apparent from the foregoing, the air flowing out of thecompartment 6 through the gap which exists between the shaft of themotor 5 and the end wall 13 makes it possible to oppose the ingress intothe compartment 6 of pressurized oxygen flowing through the gap whichexists between the shaft of the motor 5 and the wall 2 a of the volute 2that is traversed by this shaft. These respective air and oxygen leaksare collected in the chamber 7 and can be discharged by simply flowingthrough the discharge orifice 20 belonging thereto.

The deflector member 17 makes it possible to eliminate the disturbancesbetween these flows.

Moreover, the impeller 15 makes it possible to achieve a forcedcirculation of pressurized air around the motor 5, thereby providinggood cooling for the latter. The flow of this air into the collectionchamber 7 additionally allows a rapid discharge of the mixture of airand oxygen present in this chamber.

FIGS. 3 and 4 represent an apparatus 1 similar to the one which has justbeen described apart from the fact that, in this case, the orifices 11emerge into a chamber 25 separated from the collection chamber 7. Thelatter is limited to the region included between the wall 2 a definingthe bottom of the volute 2, the end wall 13 and walls 26 formed by thebody of the apparatus 1, joining that part of the compartment 6 situatedadjacent to the volute 2 to the peripheral wall defining the chamber 7.

The discharge orifice 20 belonging to the collection chamber 7 is incommunication, via a pipe 27, with the oxygen feed line 28. The mixtureof air and oxygen flowing through the aforementioned gaps is thusrecycled in the oxygen circuit.

FIGS. 5 and 6 represent an apparatus 1 in which the collection chamber 7is divided into two adjoining subchambers 7 a, 7 b, one, 7 a, of whichis defined by the wall 2 a of the volute 2 and by an intermediate wall30, and the other, 7 b, of which is defined by the intermediate wall 30and by a peripheral wall 31 attaching to the compartment 6.

As will be understood with reference to these FIGS. 5 and 6, thesubchamber 7 a is mainly intended for collecting the oxygen flow comingfrom the volute 2, whereas the subchamber 7 b is mainly intended forcollecting the air flow coming from the compartment 6. Each subchamber 7a, 7 b comprises a discharge orifice 20 a, 20 b which is specific to it,that of the subchamber 7 a being connected, by a pipe 27, to the oxygenfeed line 28. Virtually pure oxygen is thus recycled in the oxygencircuit.

The invention therefore provides a fan 1 which makes it possible underthe best conditions to solve the problem of oxygen leakage in thedirection of the motor 5, oxygen penetration not being acceptable onaccount of the risk of ignition which could result therefrom, and tosimultaneously solve the problem of cooling the motor, this motor beingsubject to significant heating on account of its high speed of rotation.

It goes without saying that the invention is not limited to theembodiments described above by way of examples but that it extends toall the embodiments covered by the claims appended hereto.

1. Fan (1) used in an apparatus for the regulated delivery of a gas, inparticular oxygen, comprising a volute (2) whose inlet opening (3) is incommunication with the oxygen feed line, an impeller (4) situatedimmediately downstream of the inlet opening (3) of the volute (2) andcomprising an inlet opening connected to this inlet opening (3) of thevolute (2) and outlet orifices (4 a) emerging into the volute (2), andan electric motor (5) for rotating the impeller (4), characterized inthat it comprises: a compartment (6) in which the motor (5) and, whereappropriate, other electric elements or components belonging to the fan(1) are placed, this compartment (6) comprising an end wall (13)traversed by the shaft of the motor (5) and being supplied withpressurized air, and a leak collection chamber (7) situatedintermediately between the volute (2) and the said compartment (6), thischamber likewise being traversed by the shaft of the motor (5) andcomprising a discharge orifice (20).
 2. Fan (1) according to claim 1,characterized in that the shaft of the motor (5) comprises at least onedeflector member (17) for separating the respective air and oxygen flowsand for orienting these flows in directions which are substantiallyperpendicular to the shaft of the motor (5).
 3. Fan (1) according toclaim 1, characterized in that it comprises an impeller (15) arrangedopposite the air inlet opening (10) belonging to the compartment (6). 4.Fan (1) according to claim 3, characterized in that the impeller (15)belonging to the compartment (6) is arranged on the drive shaft for theimpeller (4) situated in the volute (2), and is driven by the same motor(5) as the latter.
 5. Fan (1) according to claim 1, characterized inthat the walls defining the compartment (6) comprise one or moreopenings (11) emerging directly into the said collection chamber (7). 6.Fan (1) according to claim 1, characterized in that the compartment (6)comprises an internal transverse wall (12) which is distinct from thesaid end wall (13) and which is perforated by at least one hole (16) forthe flow of air across this wall.
 7. Fan (1) according to claim 6,characterized in that the said internal transverse wall (12) is formedintegrally with other walls defining the compartment (6) and serves tocentre the motor (5) in this compartment (6).
 8. Fan (1) according toclaim 1, characterized in that the said end wall (13) is composed of athin plate.
 9. Fan (1) according to claim 1, characterized in that thewall (2 a) of the volute (2) that is traversed by the shaft of the motor(5) is composed of a thin plate.
 10. Fan (1) according to claim 1,characterized in that the collection chamber (7) is divided into twoadjoining subchambers (7 a, 7 b), one of which, situated adjacent to thevolute (2), is mainly intended to collect the flow of oxygen coming fromthis volute (2) and the other of which, situated adjacent to the saidcompartment (6), is mainly intended to collect the flow of air comingfrom this compartment (6), each subchamber (7 a, 7 b) comprising adischarge orifice (20 a, 20 b) which is specific to it.
 11. Fan (1)according to claim 2, characterized in that it comprises an impeller(15) arranged opposite the air inlet opening (10) belonging to thecompartment (6).
 12. Fan (1) according to claim 2, characterized in thatthe walls defining the compartment (6) comprise one or more openings(11) emerging directly into the said collection chamber (7).
 13. Fan (1)according to claim 2, characterized in that the compartment (6)comprises an internal transverse wall (12) which is distinct from thesaid end wall (13) and which is perforated by at least one hole (16) forthe flow of air across this wall.
 14. Fan (1) according to claim 2,characterized in that the said end wall (13) is composed of a thinplate.
 15. Fan (1) according to claim 2, characterized in that the wall(2 a) of the volute (2) that is traversed by the shaft of the motor (5)is composed of a thin plate.
 16. Fan (1) according to claim 2,characterized in that the collection chamber (7) is divided into twoadjoining subchambers (7 a, 7 b), one of which, situated adjacent to thevolute (2), is mainly intended to collect the flow of oxygen coming fromthis volute (2) and the other of which, situated adjacent to the saidcompartment (6), is mainly intended to collect the flow of air comingfrom this compartment (6), each subchamber (7 a, 7 b) comprising adischarge orifice (20 a, 20 b) which is specific to it.